[Dodecanone]

So this is the problem I am trying to solve:

Calculate the r value (pm) at which a radial node will appear for the 2s orbital of the hydrogen atom. 

I know that a node occurs when the radial function = 0 but I feel like I may be making this problem too hard.  Here's the equation I'm supposed to solve for 0

R = 0 = 1/sqrt( * (1/ao)^1.5 * (2 - r/ao)*e^-r/2ao where ao is the bohr radius (52.9 pm)

Is this simply algebra or am I supposed to do something else to figure out what r is.  Thank for the *delete me*